1. Field of Application
This invention relates to surgical apparatus and methods; and more particularly to laser source surgical apparatus and methods.
2. Description of the Prior Art
Surgical procedures, especially surgical procedres wherein animal or human biological tissue, or other matter, are to be removed from a predetermined area and to a predetermined depth, require great surgical skill. In such procedures the skill of the surgeon is often enhanced by the use of apparatus particularly designed for surgical purposes. Such apparatus is more often than not very expensive, and in many instances requires complex procedures and a highly skilled or trained operator. But, regardles of the expense of the apparatus, complexity of the procedure or skill or training required to use the apparatus; it is often the availability of the apparatus that makes a particular surgical procedure possible. However, quite often the apparatus, and associated surgical method, while facilitating a particular surgical procedure, produce unwanted effects on or to areas of the human or animal adjacent to those requiring the surgery.
Laser source apparatus has been utilized for surgical procedures; especially in ophthalmology. In such apparatus a collimated beam of light, generated or produced by the laser sources, is directed so as to focus on the area to be operated on. The light energy produced by the laser is converted to heat energy which, in turn, is utilized for the surgery. Such laser source facilitated surgical procedures are sometimes and may be otherwise referred to as thermal photocoagulation as a fine controlled burn is produced. Other laser systems focus high powered pulses of light of sufficient intensity to produce optical (or dielectric) breakdown. This produces a surgical effect referred to as photodisruption because the tissues are "disrupted" by the pulsar burn and associated shock wave.
Some available laser source apparatus for those surgical purposes, and associated surgical procedures, are described: in U.S. Pat. No. 3,982,541 granted on Sep. 28, 1976 to F. A. L'Esperance, Jr., for Eye Surgical Instrument; in U.S. Pat. No. 4,309,998 granted on Jan. 12, 1982 to D. S. Aron nee Rose et al for Process And Apparatus For Ophthalmic Surgery; in U.S. Pat. No. 4,336,809 granted on Jun. 29, 1982 to W. G. Clark for Human And Animal Tissue Photoradiation System And Method; and in U.S. Pat. No. 4,391,275 granted on Jul. 5, 1983 to F. Frankhauser, et al for Method For The Surgical Treatment Of The Eye.
However, utilization of such apparatus more often than desired effects unwanted changes in adjacent remaining structures, thermal damage to areas adjacent that requiring the surgical procedure, and undesirable irregular edges of the interation site produced by the forces of optical breakdown. In addition, not every laser is suitable or acceptable if the surgeon is seeking the best possible results from the surgical procedures. A new tissue interaction has been observed using pulsed ultravoilet light. A direct photochemical effect is observed which interacts exclusively with the irradiated tissues and produces no discernible effect upon the adjacent, unirradiated tissues. For lasers generating ultraviolet wavelengths shorter than 193 nm (nanometers) it has been found that optical delivery systems become extremely difficult to build because of the limited availability of refracting material; while for lasers generating wavelengths longer than 200 nm thermal effects become more dominant and the percentage of true ablative photodecomposition lessens.
Surgical procedures may be performed using pulsed ultraviolet light utilizing a mix of complete photoablation with some thermal effect as desired by the operating surgeon.